It is proposed to investigate biogenic amine metabolism in premature infants with recurrent apneic episodes, and in the Sudden Infant Death Syndrome. Six children have been studied in longitudinal fashion with urine collection between ages 10 to 332 days. These samples were assayed for dopa, dopamine, norepinephrine, and epinephrine. When dopa concentration is divided by the summation of the active amine concentrations, an index is obtained for systemic decarboxylase activity. Preliminary data indicates a reversal of this ratio, i.e., greater than 1, to occur between the fourth and eighth month of age, correlating roughly with a peak incidence for SIDS. It is possible that should alterations in monoamine metabolism be present in SIDS, there may exist an exaggeration of enzymatic developmental processes. Brain tissue has been obtained from infants who expired with SIDS, and assayed for pyridoxal-5-phosphate, monoamine oxidase, and catechol- O-methyl transferase. For the year 01 of the research project, no control material was obtained. In comparison to adults who expired suddenly of violent means, monoamine oxidase levels were about equal, catechol-O-methyl transferase concentrations 4-7 times higher, and pyridoxal-5-phosphate levels significantly less at 1/10 adult levels. Studies of urine excretion profiles and brain tissue from SIDS children are to be continued. Similar studies will be performed on placental tissue, amniotic fluid, and cord blood obtained shortly after birth. Thus, monoamine metabolism and its possible involvement in premature apnea and crib death will be explored in a multidirectional fashion.